To study the relative role and interaction of 'Heredity' and 'Environment' in child development, which important concept was propounded by Anastasi and other psychologists explaining that development is the product of the multiplication of these two factors rather than mere addition?

The interaction of heredity and environment is a crucial topic in the study of child development. According to psychologists (especially Anne Anastasi), development is neither solely the result of heredity nor environment, but the product of their interaction. It is understood multiplicatively as both factors influence each other. Genetic structures set a potential range for development, while the environment determines the level within that range a child will reach.